1. Field of the Invention
The present invention relates to an endoscope system having an endoscope in which a hardness variation mechanism enabling adjustment of the hardness level of an elongated flexible insertion unit is incorporated.
2. Description of the Related Art
In recent years, an endoscope whose elongated insertion unit having flexibility is inserted into a region to be examined in a body cavity through the mouth or anus in order to observe the region to be examined in the body cavity without resection, or if necessary, to carry out a therapeutic procedure using a treatment appliance has been adopted widely.
The insertion unit of the endoscope has a flexible soft part so that the insertion unit can be passed through even a tortuous path. However, since the soft part has flexibility, a manipulation made proximally to the insertion unit is hardly conveyed to the distal part. The position or orientation of the distal side of the insertion unit cannot be determined as an operator intends. There is a problem that it is difficult to insert the distal part of the insertion unit smoothly into a region to be examined.
In an effort to cope with the above problem, for example, Japanese Unexamined Utility Model Publication No. 3-43802 has disclosed an endoscope in which: a coil pipe and wire constituting a hardness variation mechanism serving as a hardness varying means are incorporated in an insertion unit; and when an operator who conducts an endoscopic examination carries out a simple manipulation, if necessary, so as to adjust the degree of flexibility of the insertion unit properly, it becomes easier to insert the insertion unit into a tortuous path.
However, when the distal part of the hardness variation mechanism is located in, for example, the proximal side of a soft part composed of a distal side having high flexibility and the proximal side whose hardness level is set to a rather high level, the hardness variation mechanism works effectively in further hardening the proximal side, but fails to help adjust the hardness of the highly flexible distal side. The distal side therefore remains highly flexible. For inserting the endoscope into the rectum, sigmoid colon, descending colon, transverse colon, and ascending colon in that order through the anus for observation, an operator's manipulations made proximally are not fully conveyed to the distal part. Satisfactory obedience cannot therefore be expected. This poses a problem that it is difficult to insert the endoscope smoothly to a region to be examined.
Moreover, when the distal part of a hardness variation mechanism is located substantially at the same position as a hardness variation point of a soft part at which the hardness level of the soft part varies, if the hardness variation mechanism is hardened, an area of the soft part behind the hardness variation point gets rapidly harder while the distal side remains soft. The soft part does not therefore bend in a smooth form but bends near the hardness variation point to lose the insertional smoothness. When the soft part is bent, there is a fear that the contents of the soft part, that is, light guide fibers and channels lying through the soft part may be damaged.
In short, no mention has been made of where the distal part of the hardness variation mechanism should be located in the soft part or the practical position of the distal part.
Furthermore, in an endoscope in which the variable hardness level of a soft part of an insertion unit is adjustable, to what extent a range of levels of the variable hardness should be set has not been discussed at all.
In general, as far as a bar-like member is concerned, the harder it is, the more readily it is plastically deformed due even to a small bend. Even when a flexible variation member is hardened, the harder the member is, the more readily it buckles due to a small bend. When the coil-like flexible variation member is hardened, not only if an insertion unit is bent fiercely abruptly but also if the insertion unit is bent by a normal manipulation, the coil-like flexible variation member may be buckled depending on a hardness level present at the time of bend.
Moreover, in the case of an endoscope whose insertion unit has flexibility, the hardness level of a soft part of the insertion unit is not produced by setting the hardness level to a certain value. Assuming that a certain endoscope is regarded as a reference, when a hardness variation mechanism is added to another endoscope, generally speaking, the addition of the hardness variation mechanism to an insertion unit causes the diameter of the insertion unit to get larger or the filling factor of the contents of the insertion unit to increase. The resultant hardness level of the endoscope becomes higher than the hardness level of the endoscope used as a reference. Furthermore, the hardness variation mechanism itself exhibits a certain hardness level by nature even when it is softened most. Even from this viewpoint, the resultant hardness level gets higher than that of the reference endoscope. In other words, an endoscope having the hardness of a soft part thereof made adjustable is harder than the reference endoscope even when it is softened. With the addition of the hardness variation mechanism, the hardness level of the soft part gets even higher.
In an endoscope system having a plurality of endoscopes, when an operator uses an endoscope with a hardness adjustment function and an endoscope without the hardness adjustment function, since there is a difference in hardness level of a soft part between the endoscopes with and without the hardness adjustment function, the endoscopes lose compatibility. Since the endoscopes have no compatibility because of a difference in hardness level, an operator has a strong sense of incompatibility. Until the operator gets accustomed to the usage of the endoscope having the hardness adjustment function and exhibiting a different hardness level, the maneuverability of the endoscope deteriorates.
Furthermore, among operators using endoscope systems, of whatever types endoscopes are; a type to be used through the mouth, a type to be used through the anus, or any other types having different specifications, user-friendly endoscopes are highly demanded. Talking of, especially, endoscopes used as components of an endoscope system, there is a demand for endoscopes capable of being inserted into a region to be examined in a body cavity through the mouth or anus while giving an operator nearly the same feeling of insertion.